Our earlier laboratory studies demonstrated that a natural form of genetic transformation rapidly creates an extensive field of recombinant variation in soil populations of Bacillus subtilis. Studies in this proposal will examine additional aspects of genetic exchange by both transformation and transduction in Bacillus species populations, including: (1) patterns of variation within and between species in nature; (2) a test for the primacy of clonal versus recombining processes in natural populations at B. subtilis including a study at the dynamics of genetic change through time; (3) the effectiveness at transduction in mediating gene exchange in soil; and (4) the extent to which species of Bacillus are or are not closed genetic systems incorporating coadapted genetic systems. The association of Bacillus species in nature will also be studied as background for laboratory experiments involvving transformation across species boundaries. Health-related aspects of this research include the possibility that disease-causing and harmless species in the genus Bacillus may be capabble at exchanging genes and plasmids. In the near future, genetically engineered gene configurations in Bacillus, and other bacterial species, may also be released, intentionally or inadvertently, into nature. The research proposed will help us to plan better field testing of genetically engineered microbes, and to understand how likely it is that products of genetic engineering would circulate within natural populations and pass among species.